Used Francis Turbine For Sale
details are given for francis turbine for sale
2. HYDRAULIC TURBINE
Fundamental Technical Specifications and Main Parameters:
1 ) Main parameters Type: HLA678-WJ-6 2 Mode Horizontal Francis Rated head 76.4m Rated discharge 2.5 mils Rated output 1728 kW Rated efficiency 92,2% Rated speed 1000rimin Runaway speed 1880 Amin Runner Diameter 62 cm Suction height +1.5m Rotary direction Clockwise viewed from generator to turbine 2) Maximum Speed Variation and Maximum Pressure Variation Maximum speed variation 150%
Maximum hydraulic pressure Maximum hydraulic thrust
3) Specific Speed
4) Shaft Seal
114.6m 6.22 t 179.73m.kW
A combined sealing structure of runner with anti-thread and main shaft with water shedding ring is adopted. The shaft seal is throw ring type.
5) Draft tube Type Inlet diameter Outlet diameter Height
90′ bent draft tube 0690mm c1)1215.5mm 2500mm
Water speed medium at output the draft tubes is 2.16 mis with maximum discharge 2.5m31s.
6) Spiral case material welded metal
7) Quantity the guide vanes 16 Material of guide vanes cast steel
8) Number of Runner Vane 13 Material of runner stainless steel (ZGOCr13Ni4Mo)
9) Overhead Traveling Crane Required maximum height (from erection bay to the center line of crane hook) no less than 6 m Maximum lifting weight of the crane hook. 10 tons
10) Packing – Heaviest part – Dimension of packing case
Item Gross Weight Dimension Width ( m ) Length ( m ) Height ( m ) Main part About 10 ton 3.0 3.0 1.5
2.2 Fundamental Technical Guarantee 2.2.1 Output and efficiency guarantee The turbine shall have a guaranteed full gate output of not less than 1728 kW at turbine shaft under normal net head of 76.4 m.
Table of Output & Efficiency of Turbine at the Rated Speed & Rated Head 76.4m.
Efficiencies Rate Head Flow Power 100 80 60 45 m m3/s kW % % % % H=76.4m 2.5 1728 92.2 88.6 83.6 75.2
(The guaranteed safety operation range is within 45%-100% of the rated output) 2.2.2 Cavitations guaranteed : The measurement and calculation of cavitations erosion damage is according to IEC 609
standard. 2.2.2 Cavitations guaranteed
The measurement and calculation of cavitations erosion damage is according to IEC 609 standard.
2.3 Structure of Turbine -francis turbine for sale
The turbines are horizontal and Francis type, with a structure of 2 points of support. and horizontal water inflow is adopted. Before the inlet pipe of each turbine there is a valve with a diameter of 1600mm. An expansion joint is set between the valve and water inlet pipe. The turbine consists of draft tube, piping system, main part, runner, inlet valve and guide vane position switch.
(1) Draft tube
The draft tube includes: aeration device, bent drain pipe and conical drain pipe. The conical drainpipe is embedded in the concrete. When the unit is operating off the design conditions, the aeration device can automatically aerate the draft tube to get rid of hydraulic vibration.
The runner is welding structure and the number of the vanes is 13. The material of crown, blades and lower ring is Stainless steel (ZGOCr13Ni4Mo). The runner and main shaft is matched in conical way and torque is transmitted by flat key.
(3) Inlet pipe part
The inlet pipe part includes inlet pipe and valves. The valve includes expansion joint. The expansion joint is mounted between the valve and the inlet valve to compensate the length error and for maintenance of the unit. The inlet valve is permanently fixed in concrete.
(4) Main part
The main part includes spiral case, front cover plate, rear cover plate, guide vanes, guide vane arm, link plate and governing shaft. The number of the guide vane is 16 for adjusting the flow and load. When the unit is shut down. the guide vanes fully closed to make the speed decrease to 30% or less, and stop the unit with the brake. The guide-bearing sleeve is steel-based complicate bearing. Grease can be filled when maintenance.
For the unit, governor is used. It is connected by governing shaft, rocker arm, and connecting rod with operating ring. The governing shaft is mounted on the bearing of the governor.
Main shaft seal adopts a sealing structure of runner with anti-thread and main shaft with water throw ring. And on the water shedding ring felt sealing is used. When the shedding ring is damaged, it should be replaced and greased.
(5) Guide vane position switch
Vane position switch is set and directly connected by mounting panel and governing shaft. And the signal of vane openings can be transmitted to the main order switch. then to control chamber.
3. INLET VALVE
3.1 Specification of the Inlet valve:
( 1 ) Main parameters Type: Weighted Butterfly type with bypass valve Diameter: 700mm Operation mode: Hydraulic control design pressure 1.6 MPa ( 2 ) valve body material Q235 ( 3 ) valve disc material Q235 ( 4 ) seal material high quality antifriction rubber + stainless steel ( 5 ) the type of bypass valve hydraulic pressure bypass valve ( 6 ) diameter of bypass valve 200 mm ( 7 ) servomotor of inlet valve type straight cylinder swing type design pressure 16 MPa the number of servomotor 1 ( 8 ) Control box Quantity 1 Weight 2500 kg
3.2 The guarantee for inlet vale performance (1) The period of full open and full close time for inlet Opening time of total excursion: 60 – 90 s (adjustable) , closing time of total excursion: 60
90 s (adjustable).
(2) the full opening time and closing time for bypass valve: 20 45 s.
(3) Leakage Under the pressure action of maximum static pressure, the maximum leakage of working seal of inlet valve shall not be more than 1.36 Ifmin.
(4) Maximum unbalance water pressure permitted by inlet valve shall not be more than 6.3kg.
3. 3 Structural description of Inlet Valve
The inlet valve for is of horizontal type, double-flat-board. Its close is controlled by load and its open is controlled by operation system of the high-pressure oil pump. Each inlet valve is equipped with one set of PLC operating cabinet, and with by-pass valve, air valve. necessary piping and control device, and the expansion joint mounted at downstream side of the valve, and the mating joint mounted at the upstream side. The nominal diameter of the inlet valve is DN 700mm.
(1). Structure of valve :
It is the cast-welding structure. The valve seat is of the 7G230-450. Other parts are of 0235 steel sheets. Stainless steel are over-laying welded on the sealing part between the valve body and rubber-sealing ring, be of good anti-friction property. After weld, the annealing treatment and flaw detection check shall be done. In order to ensure the enough stiffness, the solid valve seat shall be together with the flanges. Flanges are polygon. Bracings are disposed in the flanges. It has strong strength, good rigidity and forced conditions and small distortion of sealing surface for meeting the operation requirements under the various conditions.
(2) Disc Disc has double-flat-board (or lens type) and eccentric joist frame. All ends on the outlet parts of the boards and ribs are machined for the profiles, and decreasing the cavitation effect of the stall.
For the valve of this power station, our company draws up the experience of design and manufacturing of butterfly valve, and uses the finite element strength analyze for optimization. This kind of design make the disc has enough strength and stiffness, ensure the sealing property of the valve and the hydraulic loss is least.
(3) Main seal of disc is T-type rubber or metal sealing ring, be of high-quality (SBR) material. Sealing ring assembly is closed the slots, only small part are out. Under the force conditions, the distortion is symmetrical and is of good force conditions. The main seal has flexible, the efficient compensation gap is for the disc closing, be of reliable sealing. On the full-closing position of butterfly, there is no water leakage. Sealing pressed board and screws on pressed board are made of stainless steel. The screws are used for adjusting the press of sealing rings, ensuring the reliability of sealing. In order to prevent the screws on the pressed boards loosing, all screws shall be treated.
(4) The valve shaft is made of wrought steel. Stainless steel ring shall be shrink on and then
be welded at the contact surfaces between the valve shaft and bearing and bearing journal to effectively reduce the wearing of bearing. Trunnion seal belongs to the dynamic seal. Traditional seal will be leaked after a period of work. The structure of trunnion seal produced by our company is follows: Seal of sleeve near to one end of flow passage is D-shaped paracril rubber seal (NBR). This type of seal belongs stable seal. convenient to maintain and repair. Even the flexibility of seal decrease, the seal will not be damaged and cause water flowing in heavily. Textile insertion rubber gasket seal is used at another end of sleeve. This type of seal has wide flexibility range and strong compensation ability, convenient to adjust the fasten degree according to the water leakage. This set of seal can efficiently prevent the sand entering the sleeve for decreasing the wear, improving the use life and avoid leakage.
(5) The expansion joint adopts a sleeve type structure with adjustable rubber compression amount. This kind of structure has the properties of reliable operation, convenient adjustment. little water leakage and easy disassembling and assembling. Expansion joint will not have any bad effect on the intake pipes and inlet valve by the axial force. And the expansion joint should be assembled in the workshop for strength and pressure-withstand tests
(6) Filling the spiral case with water will be done by the by-pass valve. Before the inlet valve, the penstock should be drilled a hole and set with reinforcing ring. Meanwhile the piping should be equipped with a by-pass seat to guarantee stable operation. In order to avoid excessive vibration at operation, the by-pass pipe adopts a rigid support. The diameter of by-pass piping is (p200 mm
(7) Air valve is set at the top of the flow passage of downstream of the inlet valve. It can meet the demand of exhausting when filling and aerating when closing the inlet valve. The air valve can be automatically opened and closed. And the closure is reliable and tight. The air valve is self-adaptive. Its sealing surface and spring is made with anti-rust stainless material, which has long operation life.
(8) Before the butterfly a mating section with the same diameter with the valve is set with a V-shaped welding slope.
(9) We provide the foundation bolts to be embedded in the concrete, and provide all the bolts, nuts, fillets and washers needed for connecting upstream and downstream flanges.
4. GOVERNOR 4.1 Specification of the Governor Main technical specification of the YWT series PLC governor: Type YWT-600 Capacity 6000Nm Range of adjustment for closing time: 2.5-40s Range of adjustment for opening time: 2.5-40s
be welded at the contact surfaces between the valve shaft and bearing and bearing journal to effectively reduce the wearing of bearing. Trunnion seal belongs to the dynamic seal. Traditional seal will be leaked after a period of work. The structure of trunnion seal produced by our company is follows: Seal of sleeve near to one end of flow passage is D-shaped paracril rubber seal (NBR). This type of seal belongs stable seal. convenient to maintain and repair. Even the flexibility of seal decrease, the seal will not be damaged and cause water flowing in heavily. Textile insertion rubber gasket seal is used at another end of sleeve. This type of seal has wide flexibility range and strong compensation ability, convenient to adjust the fasten degree according to the water leakage. This set of seal can efficiently prevent the sand entering the sleeve for decreasing the wear, improving the use life and avoid leakage. (5) The expansion joint adopts a sleeve type structure with adjustable rubber compression amount. This kind of structure has the properties of reliable operation, convenient adjustment. little water leakage and easy disassembling and assembling. Expansion joint will not have any bad effect on the intake pipes and inlet valve by the axial force. And the expansion joint should be assembled in the workshop for strength and pressure-withstand tests
(6) Filling the spiral case with water will be done by the by-pass valve. Before the inlet valve, the penstock should be drilled a hole and set with reinforcing ring. Meanwhile the piping should be equipped with a by-pass seat to guarantee stable operation. In order to avoid excessive vibration at operation, the by-pass pipe adopts a rigid support. The diameter of by-pass piping is (p200 mm (7) Air valve is set at the top of the flow passage of downstream of the inlet valve. It can meet the demand of exhausting when filling and aerating when closing the inlet valve. The air valve can be automatically opened and closed. And the closure is reliable and tight. The air valve is self-adaptive. Its sealing surface and spring is made with anti-rust stainless material, which has long operation life. (8) Before the butterfly a mating section with the same diameter with the valve is set with a V-shaped welding slope. (9) We provide the foundation bolts to be embedded in the concrete, and provide all the bolts, nuts, fillets and washers needed for connecting upstream and downstream flanges.
4. GOVERNOR 4.1 Specification of the Governor Main technical specification of the YWT series PLC governor: Type YWT-600 Capacity 6000Nm Range of adjustment for closing time: 2.5-40s Range of adjustment for opening time: 2.5-40s
Normal closing /opening time: 5-8 s Operating oil pressure 2.5/4.0/16.0 MPa Power supply AC220V, DC110V PID Regulator Parameter Setting Range: Proportional gain Kp 0.5-20 Integral gain K1 0.05-101/s Differential gain KD 0-10s Permanent speed droop 0-10%
4.2 Brief Introduction to the Governor
The YWT series step-motor (or digital valve) programmable microcomputer governor is a new generation governor, designed and manufactured for the small power plant, and it includes pressure oil device. This series governor includes four kind of governor model about operation capacity, whose capacity of the servomotor is 3000NM. 6000NM. 10000NM, 15000NM, 18000NM. 30000NM, 50000NM. The working pressure is 2.5/4.0MPa or 4.0MPa/16.0MPa. There dynamic and static quality are outstanding, all performance specification achieve or surpass the requirement of the IEC standards. It can make the hydro generator unit run stably under all kinds of operation mode.
Main components and characteristic of the electricity control section of francis turbine for sale:
The microcomputer governor use the Mitsubishi PLC. Use the technology of directly measurement the unit and net frequency by PLC, to raise the reliability of governor greatly.
Use the touch screen as the human-machine interface. You can observe all kinds of operation state about unit and set the parameters and operate the governor conveniently through the touch screen. The Electricity/displacement converter use the step motor and its driver .The structure is simple, operation is reliable, the requirement to oil is low. completely conquered the disadvantage of the servo valve being easy to be blocked. The YWT series step-motor programmable microcomputer governor has the main functions as follows:
Realize the starting-up , stopping , synchronization of unit in auto/manual mode, the regulation of unit load and emergency shut down .etc. The unit trace the frequency of network automatically before synchronization. and it can make the unit frequency achieve the synchronous requirement rapidly. If the network frequency has fault, it will switch to the frequency setting for starting-up automatically.
When in the manual operation mode, the output of the governor will trace the guide vane
opening automatically, and it can switch to the auto state without disturbance. The auto operation state can also switch to the manual state without disturbance. There is communication interface of host computer (Modbus RTU agreement), to realize the computer monitoring management for the whole factory, and satisfy the power plant that nobody or few person is on duty. Fault automatic diagnose online, intelligent fault-tolerant function to the fault about measurement of frequency and opening. Use AC and DC for power supply, keep the operation state of the unit and send out alarm signal at the time of the lost of AC power supply. The oil pressure device possesses the function of air supplement automatically (only apply to YWT-300, YVVT-600, YVVT-1000, YWT-1500).
Structure and Arrangement of francis turbine for sale
This governor is composed to the integral type governor cabinet by the electricity cabinet,
the mechanical hydraulic component and oil pressure device. PLC , touch screen ,
step-motor drive, switch power supply. etc. such electrical component is set in the electricity cabinet, which is isolated with the mechanical component. The adjustment maintains and checking measurement are both extremely convenient. The servomotor and leakage oil tank is connected into a body, and it connects to the distributor of turbine through the governor shaft.
5. GENERATOR AND EXCITATION SYSTEM 5.1 Type and main parameters
1) Type SFW1655-6/1430 horizontal synchronous 2) Rated speed 1000r/min 3) Rated current 178.4A 4) Rated power 1655kW 5) Rated voltage 6.3kV 6) Rated power factor 0.85 (lagging) 7) Rated frequency 50Hz 8) Rotation direction Clockwise (seen from generator to turbine) 9) Safety coefficient of rotary parts at runaway speed > 1.25 10) Reactance (rated capacity and voltage): Longitudinal axis synchronous reactance (Xd) 116.4 °A Longitudinal axis transient reactance (X’d) 25.09% Longitudinal axis sub-transient reactance (X”d) 25.09%
horizontal axis synchronous reactance (Xq) horizontal axis transient reactance (X’q) horizontal axis sub-transient reactance (X”q)
stator winding per-phase resistance ( 75°C )( R1 )
63.04% 63.04% 35.13% 0.18040
rotor winding resistance ( 75°C )( R2 ) 0.11430 11)
Time constant (1) longitudinal axis transient open-circuit time constants (Tido) 2.76s (2) short-circuit time constants of stator winding (Ta) 0.136s 12) Efficiency 7i=95.8`)/0 13) Excitation voltage at rated load 50V
14) Excitation current at rated load 375A 15) Stator (1) Material and label Stator frame Steel plate welding Stator core 50W3
15 Stator winding QZB-2/155 Stator winding insulation Insulating tape 5440-1 (2) Stator transportation mode One part (3) Inside diameter of stator 1010 mm (4) Length of stator core 480 mm (5) Stator winding Insulating class Class F Maximum temperature rise 105K Connection mode Air gap between stator and rotor 11.5 mm
16) Rotor (1) Material and label Material and label of main shaft Forged steel Rotor winding TDR Rotor winding insulation packed with epoxy diphenyl ether rubberized cloth between the turns, epoxy diphenyl ether glass for pole body
(2) Flywheel effect GD2 (3) maximum stress of rotor materials at runaway speed (4) rotor winding insulation grade Class F maximum temperature rise 105K 17) bearing Thrust bearing load 10 t Cooling water quantity 150 L/min Lubricating oil L-TSA46
< 60% of yield point
18 ) Mechanical brake Braking mode
Number of braking segments 2
Relative value of speed when mechanical brake 20-25 % Working pressure 0.5-0.7MPa Time from rated speed to stop after mechanical braking 120 s 19) Cooling system wind duct type 20) Thermal elements and temperature indicating device for generator:
Name Resistance thermal elements Type Number Thrust bearing Thrust shoe WZP-267M 2 Radial shoe WZP-267M 1 Radial Radial shoe WZP-267M 1 Stator winding and core VVZPD-60×10 6
21) Collect ring and brush Collect ring Carbon brush
22) Weight of each part of generator ( for each set ) : (1) Stator (2) Rotor (3) Front radial thrust bearing (4) Rear radial bearing 23) Largest packing: (1) Name (2) Weight 24) Heaviest part for lifting: (1) Name (2) Weight 5.2 Output and efficiency guarantee
4.5t 3.9f 1.45t 1.0t
stator assembly 5.6 t
rotor assembly 5.6 t
Output (%) 100 90 80 70 60 50 40 pf Efficiency (%) 95.8 95.7 95.6 95.5 95.1 94.6 94.0 0.85 96.1 96.0 95.9 95.8 95.4 95.1 94.6 1.0
(1) Insulation: The stator and rotor windings and the stator core are Class F. (2)Temperature rise A The temperature rise range under rated working conditions are followed:
0 Stator core (temperature detector) 100K
O Stator winding(temperature detector) 100K O Rotor winding(resistance) 105K O Collect ring( thermometer) 90K
B Under rated operating conditions, the temperature of thrust bearing and radial
bearing should not be more than 55°C and 65°C respectively.. (3) Short-circuit ratio 1.02 (4) Working voltage withstanding 15.6kV (5) Shock voltage 24kV (6) Telephone harmonic factor of line voltage < 3% (7) Excitation mode static controlled silicon excitation (8) Runaway speed 1880r/min (9) Continuous noise 1 m from the outer housing of generator (opening) is not over 85 dB (A). (10) Capacity guarantee At rated speed, rated temperature rise and voltage, the rated output of each generator is 1655 kW (1947 kVA). When the power factor is 1, the continuous capacity of each generator is not less than 1947kW. (11) Withstanding capacity of over-current Under thermal conditions, the generator stator can bear 1.5 times the rated current for 2 minutes and no harmful deformation and tip-off is permissible. (12) The generator can operate for 2 minutes under maximum runaway speed and without harmful deformation. (13) The structural strength of generator can bear rated load and terminal voltage. and in case of sudden symmetrical or asymmetrical short-circuit it can withstand for 30 seconds without harmful deformation. (14) Under normal working conditions. the permissible dual amplitude vibration of generator bearing in vertical direction should not be more than 0.07 mm.
5.3 Main construction and structure the Generator
1 ) Generator is horizontal structure with 2 supporting points and the bearing-lubricating mode is outer circulation cooling. The ventilation mode of generator is wind duct pipe cooling.
2 ) Main Performance Indexes of Generator (1) Generator shall be manufactured as per the IEC Standard. (2) When there is any change of generator load, the voltage variation is not more 12 than 5% of the rated voltage.
(3) If the three-phase short circuit appeared on the rated load and rated voltage. generator has the dynamic stability and temperature stability.
(4) The design and material of stator, rotor and auxiliary system of generator is easy to check, clean. exchange and repair.
(5) The damp-proof measures are adopted for the stop maintenance, restoring and long-term stop.
3 ) Main Structure
It is a horizontal structure with 2 supporting points and it is made up of stator, rotor, floor, front radial thrust bearing, rear radial bearing, flywheel, ventilating duct and end shield, etc.
The structure characteristics are as follows:
Stator includes frame, cone and stator windings. The stator frame is adopted integral welded structure with sufficient strength and rigidity. The base plate of generator is also integral welded structure and it has enough rigid and strength to bear the weight of each part and dynamic load, such as stator, rotor, bearing and flywheel and so on.
The cone is made by laminating fan-type pieces pressed with 0.5mm thick 50W310 low loss, high transmitting magnetism, high-grade cold rolling non-orientation silicon steel pieces. The stator core is divided into several sections which wind duct slot (width 10mm) is built in to form radial air duct.
After getting rid of burrs, both sides of stator lamination should be painted F level insulation paint to decrease vortex loss. Stator windings is lap winding, Class F insulation, Y type, having 6 outgoing lines, 3 for main outgoing lines and 3 for neutral point outgoing lines,
6 platinum heat resistances to inspect temperature of stator windings and core. The stator end shield is divided into two pieces and there is set seal gasket which is seal well and convenient to disassemble and install. .
U-shaped electric heaters with right capacity are set at both ends of the stator frame to avoid the moisturizing of the winding after long time of shutdown. The power source of the electric heaters is 380V (AC).
Structure strength of rotor and rotation parts connected with shaft should be
designed according to maximum runaway speed. Under runaway speed operate for 2 minutes without harmful distortion.
Rotor is made up of magnetic pole, main shaft and fan, etc.
Shaft is block cast and manufactured with forging steel. Magnetic cone is laminated with 2mm steel punch piece and connected with main shaft through heat hitting key. Magnetic windings are manufactured by rolling copper bands (TOR). Between layers are filled with more layers 0.16mm thick high temperature resistant epoxy glass adhesive plaster as turn-to-turn F Class insulation. Adding temperature and pressure to the whole winding placed inner of clamping instruments until copper band and insulation turn to be an integer.
Fan is drawing strickle type which has well cooling effect. Fans are erected both sides of rim. which is power source of whole wind path circulation.
When the main shaft rotates at maximum runaway speed or any speed within the runaway speed. no harmful vibration and deformation are permissible.
The main shaft should be fine-machined, supersonic detection should be done at workshop before ex-works. Reports on check and materials should be enclosed.
The front and the rear bearings are radial thrust bearing and radial seat type bearing, respectively.
The lubrication methods of bearing are all external circulation. Every one piece of PT resistance is equipped on the shoes of the front and the rear bearings and every two pieces of PT resistance are equipped on the shoes of thrust bearing for monitoring the temperature of shoes at any moment. The front and the rear radial bearing shoe are made of babbitt. and thrust-bearing shoe is made of plastic. During the operation. the structure of bearing can prevent the oil gas spilling. At the normal operation temperature, if the cooling water of bearing is intermitted, the permissible load operation can last 5 mins.
(4) slip ring and brush
Slip ring and brush are made of high anti-wearing materials. The brush layout is easy for maintenance and inspection. The slip ring and the lead wires are all oil-resistant, humid-proof. and the brush is made of silver-plated copper.
(5) lead wires
The main lead wire and the wires for neutral points are all Class F insulation of line voltage. Their numbers are both 3.
At the end of the generator, a braking flywheel is set to guarantee the necessary GD2. The flywheel is casting steel. Both dynamic and static balance tests will be performed before ex-works, and the detection qualification report is enclosed. Protective covers are set for the flywheel for guaranteeing the safe operation of the unit.
(7) Auxiliary equipment
_ Cooling system
Pipe type ventilation is employed for this unit. The hot air is drained by exhaust blower through ventilation duct at bottom of pit: while cooled air enter through at both ends of stator to form air circulation.
The lubricating system of the generator is outer circulation lubricating system and it has one set of pipeline equipments such as oil collection tank, gravity oil tank and so on. The capacity of this system is enough for the cooling requirements of the generator bearing. The lubricating oil of the bearing is L-TSAN46 (ISO VG46) turbine oil.
The brake is air pressure brake. It has two operating way of both manual and automatic modes. The flywheel is braking panel. When the speed is reduced to 20-25% of the rated value, the electro-magnetic valve can be ordered to perform continuous automatic braking or manual braking. The braking time is 2 minutes.
The braking air pressure is 0.5-0.7 MPa. Each braking segment is equipped with a position-limiting switch. When the brake piston arrives at or off the working position, the limiting device can indicate the position of the braking segment.
®Avoiding shaft current
The rear bearings are earthed. The insulation resistance is not less than 1 MO to avoid shaft current. The radial bearing at the end of the generator. cooling water pipes and thermal elements are all earthed, and the total insulation resistance is not less than 1 MO with 1000V megger at 10-30 D. And the insulating mat must be capable of bearing the relative mechanical load.
At the front radial thrust bearings one grounded brush are set.
5.4 Excitation system (with CT and PT)
Excitation Type Static silicon controlled
Technical requirements Excitation system is adopted self-shunt static silicon controlled excitation mode. It is capable of continuously running when the generator is operating at rated voltage and 1.1 times the excitation current.
The multiple of positive ceiling voltage supplied by excitation system is 1.8.
Allowable time for excitation system operation at 2 times the excitation current is 20s.
Under the condition of no-load operation of the generator and variation of frequency value is 1%, automatic excitation regulating system can guarantee that variation value of generator voltage is not greater than ±0.25% of rated value.
When fluctuation range of A.C. working power voltage of excitation regulator is in the range of 55%-120% rated value for short time (not more than continuous time of force excitation), the regulator can maintain normal operation and ensure the action of force excitation and rapid de-excitation.
Silicon-controlled rectifier is adopted three-phase full-controlled rectifying bridge-type circuit.
Double Digital voltage controllers. it is equipped with hi-performance touch screen
Normal shut-off of the de-excitation system is adopted inverter mode.
please contact with us for francis turbine for sale .